Core B continues to be responsible primarily for testing novel aromatic dicationic molecules, synthesized by Tidwell and Boykin for activity against P. carinii pneumonia (PCP) in the corticosteroid suppressed rat model of disease. New research to be performed by the core will include in vitro analysis of metabolic activation of prodrugs, synthesized by Tidwell and Boykin, prior to testing their anti-PCP activity in vivo. In addition, preliminary pharmacokinetic studies will be initiated for a limited number of selected compounds that exhibit excellent anti-PCP activity with minimal toxicity in the rat model (these advanced studies will be funded by the corporate sponsor, Pharm-Eco). Finally, this core will continue to supply organisms used in the biochemical and molecular studies by Dykstra.